This invention pertains to an improved method for recovering subterranean petroleum in situ from a petroleum-containing formation.
Many petroleum-containing formations have considerably more petroleum than can be recovered by primary production. In some petroleum-containing formations, the viscosity of the petroleum or oil is so great that little or no primary production is possible.
Various efforts and techniques have been tried to recover oil from oil containing formations where primary production is no longer economically feasible or no longer possible due to relatively high viscosity and/or insufficient pressure to move the oil to the production well for recovery from the oil containing formation or where oil was so viscous that primary production was not feasible in the first instance.
One method to increase production from an oil bearing formation in the ground is steam flooding, which entails injecting steam into an oil well and allowing the steam to remain in the formation for a selected period of time (often referred to as the soak period). The viscosity of the oil is reduced and some gas is generated by the heating of some lighter oil in the formation. The gas provides pressure to force the thinned or less viscous oil to the oil well. Often the pressure is short lived and relatively little additional oil is recovered by this technique.
Another method of enhancing production of oil from an oil bearing production is a steam drive process in which steam is injected into the oil bearing formation in a more or less continuous fashion through an injection well and oil is recovered from the formation from a spaced-apart production well. A disadvantage of this technique is that often steam will channel across the top of the oil bearing formation and in effect impede recovery of oil from the bottom or lowermost portions of the formation.
Water flooding is another technique that has been employed for recovery of oil from partially depleted oil bearing formations after termination of primary production. Water is injected into the oil bearing formation at various locations where the water can displace the oil and force it toward and into production wells. This technique is not too successful in some oil bearing formations, for example, where the oil is too viscous, where the formation is too permeable, and where the formation is relatively deep in the ground.
Leeper U.S. Pat. No. 3,605,885 suggests a technique of enhancing secondary recovery of oil from oil containing formations by injecting heated gas and steam into an injection well for heating the oil in the oil bearing formation to reduce its viscosity.
The present invention comprises an improvement over the subject matter disclosed in the Leeper patent and pertains to an improved method for increasing the production of oil from an oil bearing formation.
An object of this invention is to provide an improved method for secondary recovery of oil from oil bearing formations, including shale formations, wherein the disadvantages and deficiencies of present methods of secondary recovery are overcome.
Another object of the present invention is to provide an improved method for recovering oil from oil containing formations using heated and pressurized combustion byproducts which have been rendered inert by contact with manganese and/or manganese dioxide and which are injected into the oil bearing formation at predetermined pressure and temperature conditions to render the oil in the oil bearing formation less viscous and to force it to the production well for recovering more oil from the oil bearing formation.
Another object of the present invention is to recover oil from shale oil bearing formations by injecting combustion byproducts heated to temperatures within the range of 900.degree.-1200.degree. F. to free oil from the shale oil bearing formation.
Yet another object of this invention is to provide an improved method of oil recovery from an oil bearing formation wherein the production wells and injection wells are arranged to help maximize the oil recovered.
Other objects and advantages of the present invention will be made more apparent hereinafter.